A former SAS sergeant has denied at the Ben Roberts-Smith defamation trial that his memory loss extends to significant "details" while taking medication for multiple mental health conditions.
The special forces soldier codenamed Person Four on Tuesday in the Federal Court was formally excused by Justice Anthony Besanko from answering questions about a 2009 mission dubbed Whiskey 108.
The fresh trooper at the time is accused of shooting a prisoner under orders in effect to "blood the rookie," a phrase referencing a junior soldier getting their first kill in action.
But after objecting that he did not want to "self-incriminate," it was accepted the evidence risked further prosecution by the International Criminal Court and was not pressed.
However, he did say he was made aware the media outlets who seek to rely on a defence of truth were alleging he had murdered an unarmed Afghan male in 2009.
After rising through the elite soldiers' ranks to sergeant, Person Four was medically discharged from the Australian Defence Force in 2021.
Details of his mental health disorders and the medications he takes were also suppressed by the court.
As a result he suffers from some "mental impairment," and "memory loss" on occasion, "ruminating thoughts" and "flashbacks" about his time serving in the defence force.
At times he has trouble sleeping, difficulty concentrating, and recalling specifics.
"I think the minutia of things was fading away, small details, large details definitely not," he said.
But he denied assertions by Arthur Moses SC on behalf of Mr Roberts-Smith that he experienced "hallucinations" was "hearing things that are not real", was worried "someone is trying to harm you," or heard "people screaming".
"Have you discussed with your psychologist what is real and what is not?" Mr Moses said.
"Absolutely not," Person Four responded.
He also denied there was any "confusion about events you think you've experienced".
After refusing to speak with journalists, Person Four said another soldier approached saying there was "someone you should talk to".
He believed it was to "discredit" Mr Roberts-Smith to a journalist because this soldier "disliked" him.
Mr Moses asked if it was fair to say there were rumours this soldier codenamed Person Six wanted to bring Mr Roberts-Smith down.
"That's correct," Person Four said.
Mr Roberts-Smith, 43, is suing The Age, The Sydney Morning Herald and The Canberra Times over reports that he committed war crimes and murders in Afghanistan between 2006 and 2012.
One of a handful of Australian recipients of the Victoria Cross since 1970, he has suggested some claims stem from jealous associates spiteful of his medallic achievements.
Person Four on Monday said he witnessed Mr Roberts-Smith kick an unarmed and handcuffed Afghan prisoner off a "steep slope" in the village of Darwan, Uruzgan province in September 2012.
Person Four said he could see the prisoner's face strike a large rock and sustain a "serious injury," before he was shot dead near a creek bed.
Mr Roberts-Smith vehemently disputes the allegation and testified he was in fact a Taliban spotter shot in a cornfield.
Person Four alleges an Icom radio Mr Roberts-Smith had retrieved from another insurgent was planted on the body and included in a photographic cover-up of the unlawful killing.
Person Four who is "reluctantly" giving evidence in court is due to return on Wednesday.
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